Boom assemblies are commonly used on agricultural vehicles and implements, such as sprayers and planters, to dispense seed, fertilizer, insecticide and herbicide over the large surface area of a field during a pass across the field. Such boom assemblies typically include a central support and at least one wing pivotably mounted to the central support to permit the wing to pivot in either direction out of its desired transverse spraying or planting position in response to being contacted by an abutment such as a post or tree. To return the wing to its neutral transverse spraying or planting position, some boom assemblies include springs or elastic cables of equal force connected to opposite sides of the wing.
In addition to being pivotable forward and rearward of the desired transverse spraying or planting position, the wing is also pivotable from the desired transverse spraying or planting position to a folded position which extends substantially parallel to the implement or vehicle supporting the wing. In the folded position, the wing and the boom assembly itself are better suited for transport. Pivoting the wing from the generally transverse spraying or planting position to the folded position typically performed either manually or by a single hydraulic cylinder piston mounted between the boom and the central support.
Although such boom assemblies are commonly employed on agricultural vehicles and implements, such boon assemblies have several drawbacks. First, such boom assemblies require multiple components: multiple springs to return the wing to the desired spray position after hitting an obstruction and a hydraulic piston cylinder assembly to pivot the wing to the folded position. This multitude of components increases the cost and complexity of the boom assembly. Secondly, during movement of the wing to the folded position, one of the two springs actually works against the hydraulic cylinder piston assembly. As a result, the spring is either stretched, which reduces its useful life, or must be disengaged. Third, such boom assemblies provide limited control over the rate at which the wing pivots in response to engaging an obstruction.
Thus, there is a continuing need for a boom assembly having a pivoting wing which requires fewer parts, which may be easily moved between a spraying or planting position and a folded position and which provides greater control over the rate at which the wing pivots.